The fabrication of semiconductor devices begins normally with the patterning of various features on and into semiconductor wafers. Afterwards the processed semiconductor wafers are singulated into semiconductor dies. In order to facilitate the attachment of these semiconductor dies to boards like printed circuit boards (PCB) and to protect the semiconductor dies, the semiconductor dies are typically assembled into packages before connecting them to a PCB. Up to now different types of semiconductor packages have been developed, one of which is the ball grid array (BGA) package. A BGA package connects to a PCB through an array of solder balls, which take the place of the pins of the solder pin-grid array packages.
Semiconductor packages often undergo reliability stress tests in which, for example, PCB-mounted BGA packages are typically subjected to temperature cycle testing, in particular the so-called Temp-cycle-on-Board (TCOB). These tests provide an indication on how the semiconductor device will perform in the field. Special semiconductor packages, in particular in automotive applications, are facing continuously increasing TCOB requirements. One important point of failure for BGA packages in TCOB testing is the solder ball connections. For improving the reliability of package to board connections, it is therefore important to improve the condition and reliability of solder ball connections.